**4.3 Leishmaniasis**

It is the second most prominent parasitic infection after malaria in terms of fatalities caused by it globally. The phlebotomine sandflies are the prominent vectors of leishmaniasis, mainly found in tropics and subtropics [27]. For its vector control, the chemical interventions used are IRS and ITNs. Since 1944, DDT-based IRS was mainly used for the control of sandfly, but after 1970s, due to its toxic effect and reports on DDT resistance in sandfly from the disease endemic regions in India resulted in the use of alternative insecticide, i.e., pyrethroids [28, 29]. The deltamethrin, lambda-cyhalothrin and alpha-cypermethrin resulted in more

than 70% of reduction in both *Lutzomyia* spp. and *Phlebotomus argentipes* sandflies [30]. Insecticide-treated durable wall lining (DWL) is being used as an alternative type of indoor residual intervention to increase the residual effect of insecticides used in IRS [31] and it drastically reduced the abundance of *P. argentipes* in south Asian countries [32]. Presently, IRS spraying and use of ITNs are the most common methods implemented in vector control programmes for the control of sandfly.

#### **4.4 Human African Trypanosomiasis (HAT)**

HAT is transmitted by the bite of the tsetse fly, i.e., *Glossina* spp., across most of the 38 countries of the sub-Saharan Africa [33]. In 1945, DDT and BHC were the only synthetic insecticides used for their control, but later on pyrethroids like deltamethrin were used. In Ethiopia, deltamethrin impregnated nets were used in 1990 for the control of *Glossina pallidipes* [34], but later on resistance was reported to deltamethrin [35].

### **4.5 Chagas' disease/American trypanosomiasis**

The Chagas' disease, transmitted by triatomine bugs, is a major disease affecting millions of people in the Latin America countries. In 1950s, DDT was used to control the triatomine density [36], following which HCB was considered to be more effective, and later, dieldrin was also used for its control. In 1999, resistance in triatomine bugs was not a serious problem except for some reports where *Rhodnius prolixus* showed resistant to pyrethroids in Venezuela, and *Triatoma infestans* in Brazil [37, 38]. Some reports of deltamethrin resistance in *T. infestans* are also there from Argentina [37]. In a study carried out in Bolvia also, *T. infestans* populations were found resistant to deltamethrin [39]. The expression of resistance to pyrethroids during the early phase of embryonic development in *T. infestans* has also been reported [40]*.*
